Piston rod protector



T. K. HELMER PISTON ROD PROTECTOR Filed April l?, 1936 Dec. 21, 1937.

Patented Dec. 2l, 1937 UNITE-oysTATEs PATENT OFFICE 2,102,797 PISTON ROD PROTECTOR Theodore Kenneth Helmen', Fellows, Calif.

" Application April 1i.

10 Glaims.

This invention relates generally to protectors for pumps and the like, ,and specifically contemplates a collapsible cylindrical enclosure fior Ythe rod of a reoiprocatingepiston type pump, thereby to separate the bearing and packing element from abrasive substances in the fluid to be pumped- While the device of my invention as herein-V after described may be Iliade .adaptable for use in a wide variety of types of pumps, the accomppanying disclosure will be diretedto an emblidi ment thereof. .Particularly applicable to slush pumps commonly employed' in welldrllling.

AS is well known, the mud fluid circulated through the bore of deep wells drilled by rotary methods is composed of materials to form a consistency of suilcientweight to maintain in sus.- pension drill cuttings .and savings, until they may be raised in the '.iluid to the surface ofthe well for deposition in a settling ditch.. .Materials eccnoln.-v ically available for such fluid necessarily include abrasive particles which must pass through the pump for circulation in the well.V furthermore, the density of the mud precludes the entire -removal of the'detrtal material taken from the Well or even the substantial cleansing of the iiuid'. except by excessively expensive methods, 'before it must again be returned to the /well bore by the slush. pump.

The extremely high pressure often utilized in such pumps of the well drilling art tends to force these abrasive particles carried by the fluid metia vated, as well asthe original attrite constituents of the mild, into the, kbearings and packing of the piston rod, which results in excessive wear with a :consequent loss in-eiliclency and necessitates frequent replacement of, the parts. l c

Itis a principal object of the present invention to provide a lprotector for. the pistonvrod of reciprocating pumps whereby a separate chamber is for-med `withinthe pump cylinder for the reciprocation of -the rod which isolates-the bearings and pa'ckinglelements withV respect tothe working chamber of the pump to prevent contamination thereof by abrasive materials carried in the fluid' motivated by the pump.. j

Another object is toprovide a flexible `cylinder forming [a sealed collapsiblev chamber between tnepistcn and cylinder end wall'of the working chamber of a reciprocating pump'in which the piston rod is adapted to operate, embodying meansactuated by the working pressure oi the pump to .correspondingly vary the pressure within the sealed chamber and thereby obviate the.

1936, Serial No.. 74,938

formation of a Ypressure dillerential between the zones within and around the flexible cylinder.

Another object is the provision of a device easily applied to oil well slush pumps as at present designed for they art.l which is simple in construc- 5 tion, facilitating lrcplacement Vcf worn parts. economical in manufacture and efficient in opera--r tion.`

Other objects will be apparenti() those of skill in the art to which the present invention appertains upon an examination ofthe following description read in the light of the accompanying drawing, in which-H Fig. l is a sectional view of my invention as applied t0 the Piston and rod of a double acting slush pump;

Fig. 2 is an enlarged fragmentary sectional View of the attachment of the flexible cylinder to the end `wall of the ,working chamber of .the pump;

Fig. 3 is a sectional view similar to Fig. 2 illusa trating the attachment of the flexible cylinder i0 the piston;

Fig. 4 is a sectional view of aimodied'form of pressure tank.

Referring to the drawing in detail, the numerals of which indicate similar'parts throughout the several views', 5 designates generally the portions .of the body of a slush pump which are adjacent .the working chamber 6 of the pump- The details of the Pump, -Whichmay be of. any type well l lsnown in the art. .are not illustrated or further described. A steel liner l is provided in the body 5, in which a piston 8, later referred to, is adapted to reciprocate. Y

Through a bearing 9 in .the end wall I ll of cham-.- ber 6 of the body of the pump and concentrically into the liner 1 a piston rod II extends. The various drive mechanism for the reclprocation of the piston rods are likewise ,familiar to thev art, and forming no part of the present invention, are not set forthv Y Y Integral with the outside .of the end wall l0. a stuiiing box I2 encircles rod II in which packing I3 is compressed by a gland 1,4 in a well known manner. Near the end of rod II Within liner "I, the diameter of the rod is increased to form a beveled shoulder I5; A concavo-convex washer I6 having its concave surface corresponding to the bevel of shoulder I5 is arranged on rod II adjacent the shoulder against which a similarly shaped concavity I1 of piston head I8 is adapted to seat. A nut I9 threaded on the end of rod II clamps the piston 8 and Washer I6 rigidly against the shoulder I5.

.im annular rim rZll of washer I6, projecting from between piston head I8 and shoulder l5 of the rod is turned inwardly, substantially parallel with the rod. One end of a cylinder 2|, composed preferably of rubber or other flexible impervious material, encircles rim and is secured in a groove 22 formed on the periphery of the rimby means of a hose clamp 23 to provide a fluid-tight connection.

The opposite end of the cylinder 2| is similarly attached by hose clamp 24 on the periphery of a collar 25 which encir'cles rod Collar 25 is threaded on a hub 26 which is welded or otherwise secured to the end wall 'I0 around rod Studs 2? are radially mounted on collar 25 to facilitate attachment and removal thereof relative to the hub.

From the above description it will be apparent that fluid drawn into the working chamber 6 of the pump, and which is compressed on the opposite stroke of the piston, Will not contact rod I or end wall IU adjacent bearing 8 at any time during operation of the pump.

To prevent fracture of the cylinder2| as the piston is moved on its pumping stroke,pressure within the flexible cylinder is maintained substantially equal to that outside thereof by communication of the space within and around the cylinder with a variable pressure tank 28 about to be described. Tank 28 is preferably constructed in two sectionsV 29 and 39, between the abutting edges of which a flexible membrane 3| is secured to divide the tank into chambers 32 and 33. A tube 34 extending from chamber 33 is connected with a passage 35 through end wall I0 which opens into the bore of hub 26 around the rod, thus communicating the space within the cylinder 2| with chamber 33 of the tank. Chamber 33 and the cylinder 2| are lled with a fluid of substantially the same density and compressibility as the uid passing through the pump. Another tube 36 connects, through a hole 31 in the wall of section 29 of tank 28, the working chamber 26 with chamber 32 of the tank.

It will thus be seen that pressure in the cylinder 2| and chamber 33 will be maintained equal to the pressure within working chamber 6 and chamber 32 by the resiliency of membrane 3|. Any tendency toward a pressure differential during operation of the pump between the spaces within and around the cylinder 2| coincidentally influences pressure Within their respectively-connected chambers 33 and 32 of tank 28. Membrane 3| will accordingly obviate the creation of a pressure differential between the spaces within and around the flexible cylinder, which might result in distortion or fracture of the cylinder, by expanding int-o the chamber of the lowest pressure.

A container 38 for additional fluid for chamber 33, to compensate for loss by leakage, or to facilitate filling or draining of the tank during replacement of the membrane or flexible cylinder 2|, is connected by a pipe line 39 extending through section 39 into chamber 33 of the tank. A hand pump 40 of a type wellknowri in the art isY disposed in pipe line 39 to impel fluid from the container 38 v to chamber 33. A pressure gauge 4| of a wellknown type is located in pipe line 39 to enable accurate measurement of the injection of the fluid into tank 28. After assembly of the pump, and my invention therewith, a valve 42, provided in the wall of section 29, should remain open during the first stroke of the piston to compel pressure fluid from the working chamber to expel air or other highly compressible gas trapped therein.

A modified form of pressure tank is illustrated in Fig. 4, comprising a cylinder 43 in which an annular piston 44, having an opening 45 therein, is adapted to move. A flexible membrane 46 is attached to the piston over opening 45, by well known means, to divide the cylinder into chambers 41 and 48 at opposite sides of the piston. The ends of the cylinder'are communicated with the pump in the manner above described in detail, by means of nipples 49 threaded into holes 5.9fin the cylinder. Abutments 5| are secured in the cylinder bore adjacent each nipple 49 to limit the stroke of the piston to the zone between holes 50, thereby enabling the slightest differential in pressure between the chambers at opposite sides of the piston to move the piston and membrane for the purpose above indicated in the description of the embodiment illustrated in Fig. 1.

It should be understood that numerous changes may be made in the embodiments shown as to size, proportion, relative arrangement and design of the various parts; that a solid piston may be substituted for the annular piston illustrated in Fig. 4 or the membrane shown in Fig. l; and that other means well known in the art may be employed for releasably attaching the flexible cylinder to the piston and end wall of the worln'ng chamber of the pump, without departing from the spirit of my invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. In a pump having a cylinder in which a piston is reciprocated by means of a piston rod, a flexible enclosure around the piston rod between the piston and end wall of the cylinder, means to seal the zone within the enclosure with respect to the area around the enclosure, and means to regulate -pressure within the enclosure by pressure around the enclosure.

2. In a pump having a cylinder in which a piston is reciprocated by a piston rod, a collapsible enclosure encircling the rod between the end wall of the pump cylinder and the piston, means to connect the ends of said enclosure to, respectively, the piston head and end wall of the pump cylinder, thereby separating the piston rod from the effective working area of the pump, and means to maintain equal pressure within and around the enclosure.

3. In a reciprocating piston'type pump, a collapsible enclosure encircling the piston rod having one end connected to the end wall of the pump cylinder and its other end connected to the piston, a container, a wallV dividing said container into two chambers, said wall being movable to vary the size of the chambers upon the creation of a pressure differential between the chambers, and communicating means from opposite chambers to,- respectively, the zones within and around the collapsible enclosure.

4. In a reciprocating vpiston type pump, a collapsible enclosure to separate the portion of the piston rod which contacts the end wall bearing of. the Vrod from the effective working area. of the pump, a container, means to communicate pressures created in, respectively, the zones within and around said enclosure by reclprocation oi' the piston to opposite ends of said container, and a movable wall dividing the container into two chambers adapted to reduce the size of one of said chambers .by increased pressure in the other.

5. In a pump, a cylinder, an end wall for said rod connected with said piston and journalled in a bearing in said end wall, enclosure means to enclose the portion of the rod contacting the bearing with the portion of the end Wall adjacent said bearing to thereby isolate the bearing with respect to the effective pumping area of the cylinder, and means to equalize pressure Within and around the enclosure means.

6. In a pump, a cylinder having an end wall, a piston in said cylinder, a piston rod journalled in said end wall having a bevelled annular shoulder, a bevel-faced washer of a width greater than the width of said shoulder and adapted to seat on said shoulder, the said piston adapted to seat on said washer, a collapsible enclosure encircling said rod having one end secured to said washer, means to maintain a lluid tight fit between said Washer and enclosure, and means to removably secure the opposite end of said enclosure to said end wall.

'7. In a pump, a cylinder having an end wall, a piston in said cylinder, a piston rod journalled in said end wall carrying a bevelled annular shoulder, a, bevel-faced washer of a width greater than the width of said shoulder and adapted to seat on said shoulder, a piston adapted to seat on said washer, a collapsible enclosure encircling said rod having one end secured to said Washer, means to maintain a uid tight fit between said washer and'enclosure, means to removably secure the opposite end of said enclosure to said end Wall, and means to regulate pressure within said -enclosure by pressure created around .said enclosure.

8. In a device of the character described, a pump cylinder, a piston rod extending into said cylinder carrying a bevelled annular shoulder, a washer having its opposed annular faces parallel to said shoulder, said washer having an annular flange at its edge, a cylindrical flexible enclosure encircling the piston rod having one end sealed to said ange, means to connect the otherV end of said enclosure to the end wall of the cylinder around the piston rod, and a piston having a conical convexity concentrically formed therein adapted to seat on said washer.

9. In a pump, a body having a pump chamber therein, a bearing in said body, a rod extending through said bearing, a piston within said pump chamber connected to said rod, a flexible inclosure around the portion of said rod adapted to contact said bearing, means to seal the opposite ends of said inclosure with the rod and body, respectively, and means to regulate pressure Within the inclosure by pressure around the inclosure.

10. In a pump, a body having a pump chamber therein, a bearing in said body, a rod extending through said bearing, a piston within said pump chamber connected to said rod, a flexible inclosure around the portion of said rod adapted to contact said bearing. means to seal the opposite ends of said inclosure with the rod and body, respectively, and means to maintain pressure Within the inclosure substantially equal to the pressure around the inclosure.

'I'I-IEODORE KENNETH I-IELMER. 

